Choosing blood pressure thresholds to inform pregnancy care in the community: An analysis of cluster trials

Abstract

Objective: To inform digital health design by evaluating diagnostic test properties of antenatal blood pressure (BP) outputs and levels to identify women at risk of adverse outcomes. Design: Planned secondary analysis of cluster randomised trials. Setting: India, Pakistan, Mozambique. Population: Women with in-community BP measurements and known pregnancy outcomes. Methods: Blood pressure was defined by its outputs (systolic and/or diastolic, systolic only, diastolic only or mean arterial pressure [calculated]) and level: normotension-1 (<135/85 mmHg), normotension-2 (135-139/85-89 mmHg), non-severe hypertension (140-149/90-99 mmHg; 150-154/100-104 mmHg; 155-159/105-109 mmHg) and severe hypertension (≥160/110 mmHg). Dose-response (adjusted risk ratio [aRR]) and diagnostic test properties (negative [−LR] and positive [+LR] likelihood ratios) were estimated. Main Outcome Measures: Maternal/perinatal composites of mortality/morbidity. Results: Among 21 069 pregnancies, different BP outputs had similar aRR, −LR, and +LR for adverse outcomes. No BP level (even normotension-1) was associated with low risk (all −LR ≥0.20). Across outcomes, risks rose progressively with higher BP levels above K E Y W O R D S blood pressure thresholds, community, digital health, pregnancy